1. Field of the Invention
The present invention relates to a semiconductor package that is simply structured at low cost and to a semiconductor mounting part therewith.
2. Description of the Related Art
In recent years, as semiconductor fabrication technologies have been remarkably advanced, high integration and high power of semiconductor chips have been accomplished. Thus, the amount of heat generation of semiconductor chips has been correspondingly increased. In addition, the number of input/output signals per chip has been increased.
In these situations, packages that mount highly integrated semiconductor chips and so forth should effectively radiate heat generated by the semiconductor chips and have many terminals connected thereto at narrow pitches.
With respect to heat radiation of semiconductor packages, as portable electronic units and so forth have been advanced, heat radiation characteristic in natural convection state should be improved. In addition, as the sizes of electronic units are being decreased, the sizes of the semiconductor packages should be decreased.
In a conventional method for mounting a semiconductor chip with a large number of input/output terminals on a package, a semiconductor chip is bonded to a so-called TAB (Tape Automated Bonding) tape and the TAB tape is mounted on a package.
In the conventional package structure using the conventional TAB chip, however, the TAB chip is mounted on a package substrate composed of a multi-layered ceramic wiring board or a multi-layered resin wiring board. A wiring layer of the package substrate and TAB leads are connected. Thus, structurally, this package is expensive.
As another related art reference, an inexpensive package of which a TAB chip is sealed with a resin is known. However, in this structure, the heat radiation characteristic is remarkably low. Thus, this package cannot be used for such a highly integrated semiconductor chip and so forth.
As a further related art reference, a BGA (Ball Grid Array) type package using a TAB chip has been proposed. As shown in FIG. 7, in the BGA type package, a metal frame 3 or the like is bonded to a TAB tape 2 on which a semiconductor chip 1 is mounted so as to prevent so-called lead skewing such as bending and distortion of leads. However, in this structure, the heat radiation characteristic cannot be improved. Even if a heat radiation plate 4 is disposed at an upper portion of the metal frame 3, since a sealing resin 5 and so forth are disposed between the heat radiation plate 4 and the semiconductor chip 1, sufficient heat radiation characteristic cannot be obtained.
As a low heat resistance package with a high heat radiation characteristic, a so-called cavity-down structure type package has been proposed. In the cavity-down structure type package, as shown in FIG. 8, a semiconductor chip 1 is bonded on a lower surface side of a high heat radiation supporting substrate 6 composed of an aluminum nitride substrate or the like. A wiring portion 7 composed of a printed wiring board or the like is bonded on the same surface as the bonding surface of the semiconductor chip 1.
Although the cavity-down structure type package has; relatively high heat radiation characteristic, when the number of input/output signals increases, the package size becomes large. Thus, the requirement for decreasing the package size cannot be accomplished. In addition, as the package size increases, since the wiring length becomes long, electric characteristics such as wiring resistance and inductance degrade.
As described above, the conventional semiconductor packages that are simply structured at low cost have the following drawbacks. In the case of the package structure using a TAB chip, sufficient heat radiation characteristic cannot be obtained. In the case of the low heat resistance package having the cavity-down structure using the high heat radiation supporting substrate, when the number of input/output signals increases, the size of the package becomes large. Thus, the requirement for decreasing the package size cannot be satisfied. In addition, in this structure, electric characteristics are also degraded.
Thus, in the conventional semiconductor packages, the cost should be decreased in a relatively simple structure. In addition, both the improvement of heat radiation characteristic and the decrease of the package size should be satisfied. Moreover, the electric characteristics should be improved.